Lightning Arrester, while undefined but currently used throughout the industry, and Surge Arrester are interchangeable surge protection terms. Arresters are surge protectors but are vastly different from a Surge Suppressor i.e. Transient Voltage Surge Suppressor (TVSS). Prior to September 2009, Lightning Arrester / Surge Arresters and TVSS had basically the same function but were regulated by two different entities. Arresters were evaluated under the IEEE standard C62.11 and were subjected to almost no safety testing while TVSS were evaluated under UL 1449 and rigorously safety tested.

Post September 2009, UL 1449 and 2008 NEC Article 285 require lightning arrester / surge arresters and TVSS for electrical systems rated under 1000 volts to follow the Surge Protective Device (SPD) requirements. These surge protectors (SPDs) are subjected to rigorous safety testing and effectively obsolescence the usage of the former terms in these applications. The term arrester now only applies to surge protectors for electrical systems rated above 1000 volts. These arrester applications are covered by Article 280 of the NEC.

Arresters are typically installed on transmission lines and they divert lightning and utility switching surges to ground, clamping (or limiting) the voltage of the surge. Their function is similar to that of a hardwired SPD that is installed inside a facility. They are generally MOV-based like an SPD, but unlike an SPD they have no safety disconnectors. Their lack of safety disconnectors makes them susceptible to violent failures (i.e. explosions). This was the main reason lightning arrester / surge arresters under 1000V were regulated obsolete.

APT designs and manufacturers hardwired Surge Protective Devices that meet all applicable codes and standards. Contact the factory today for more information on products and training.

A "surge" is a transient wave of current, voltage or both in an electric circuit.  Be aware that "surge" and "power surge" carry a layman’s connotation of almost any type of power disturbance, which differs from technical definition.  Within the electrical standards community, the term ‘power surge’ approaches nebulous, inviting further information.  "Surge" is more formally defined as a transient overvoltage or transient sub-cycle event, and not as an event that increases power frequency voltage for multiple cycles.  Multi-cycle overvoltage events are more aptly named temporary overvoltages (TOVs), designating a similar sounding, but substantially different power anomaly.  As an oversimplification, surges are caused by switching or lightning disturbances.

To learn more about surge protection watch this new video "What is a Power Surge?" from our residential division, surgeassure, and check out these surge protection FAQ's.